Many hand-held devices use either non-rechargeable (primary) or rechargeable (secondary) cells for drawing power. Common cell sizes are AAA, AA, C, D, and the like. Using rechargeable cells is a preferable on-going cost savings option for the user and provides a positive environmental impact. However, one drawback of using rechargeable batteries is the constant requirement placed on the user to periodically remove the cells and place them in a charger, or to plug in a specific cell charger to the particular device used.
“Trickle charging” in the context of rechargeable batteries is well-known in the art as charging a battery at a rate close to its self-discharge rate. All rechargeable batteries slowly discharge themselves over a period of perhaps many hundreds of hours. “Trickle charging” keeps a battery ‘topped up’. If a battery has a capacity C, then it may perhaps be allowed to be charged at a rate C/8 which means that it reaches full charge in 8 hours. That would be a typical charge rate. “Trickle charging” would be at a rate of perhaps C/100 (or lower (i.e. to charge it from fully discharged at the trickle rate it would take 100 hours or more).
Wireless recharging of batteries is a known technology, used widely, for example, in battery operated electric toothbrushes. In these the toothbrush is rested on a recharging base when not in use, the base containing the primary coil of a transformer. The secondary coil of the transformer is in the handle of the toothbrush. Power is coupled magnetically to charge the cells in the toothbrush. This is a very purpose specific application as it operates with a closely coupled transformer at relatively low frequency.
Wireless recharging where the power receiving circuit is custom built into the hand-held device is also known. Splashpower® is one vendor offering such wireless recharging capability.
Beart et al. disclose, in U.S. publication no. 2006/0043927 A1, issued Mar. 2, 2006, a system and method for retaining portable rechargeable devices to recharging stations wherein one or other or both of the recharging station and the portable device are provided with connecting means adapted for temporary releasable connection of the two.
More specifically, Beart et al. disclose a mobile phone that has a connecting means attached to the back of the mobile phone. Beart et al. discloses that the connecting means is a patch of self-adhesive Velcro®. Further, Baert et al. discloses that the connection means can be in the form of suckers, reusable self-adhesive glue, or other forms of high “stiction/friction” surfaces.
The adhesive layer discloses by Beart et al. is on the outside of a wireless device's casing.
Naskali et al. disclose in U.S. Pat. No. 7,180,265 B2, issued Feb. 20, 2007, an apparatus and method for a charging device which includes a battery having a first induction coil coupled to the battery, and an induction core extending through the first induction coil. The induction core has a portion which extends in an outward direction from the charging device and is adapted to removably couple with a second induction coil of a portable electronic device by extending into the second induction coil.
Rahmel et al. disclose in U.S. Pat. No. 7,268,517 B2, issued Sep. 11, 2007, a system for harvesting radio frequency energy from the atmosphere and redirecting the energy to wirelessly power electrical devices. More specifically Rahmel discloses an energy harvesting subsystem (EHS) which pulls free RF energy out of the atmosphere and redirects the energy using energy conversion subsystem (ECS). The ECS rectifies energy to convert it and send it to a transformer and a trickle charger. The transformer and the trickle charger are designed to match impedances to prevent undesired energy loss between the two elements. The trickle charger delivers the energy to the rechargeable battery for storage to be used later by stand-by devices.
Despite these and other efforts in the art, still further improvements in the area of wireless power supply which requires no electrical or mechanical connection between the power transmitter and the power receiver would be desirable.